Ventilating means for light source for projector

ABSTRACT

A projector having a molded plastic outer case which is supported by a curved steel stand which also serves as an elevating device and carrying handle. The projector can be tilted simply by sliding it up on the curved stand and locking it with two knobs. An electric lamp is mounted at a center location within the case and a pair of heat dissipating baffle plates are positioned on opposite sides of the lamp. A cover is positioned over the lamp and baffle plates to direct the cooling air rising adjacent the lamp toward the rear of the projector. A film advance mechanism is housed in the case and includes an arm which engages the film sprocket holes only during the advancing operation.

United States Patent [72] Inventor Eugene Martinez lrvington, NY. [21] Appl. No. 10.344

[22] Filed Feb. 11, 1970 Division ofSer. No. 715,621. March 25,1968, Pat. No. 3.520.599

July 13, 1971 Robert H. Relbel Croton-on-Hudson, NY.

a part interest [45] Patented [73] Assignee [$4] VENTILATING MEANS FOR LIGHT SOURCE FOR [56] References Cited UNITED STATES PATENTS 1/1933 Davidson 353/119X Primary Examiner-Sam uel S. Matthews Assistant ExaminerT. A. Mauro Attorney-.1. B. Felshin ABSTRACT: A projector having a molded plastic outer case which is supported by a curved steel stand which also serves as an elevating device and carrying handle. The projector can be tilted simply by sliding it up on the curved stand and locking it with two knobs. An electric lamp is mounted at a center location within the case and a pair of heat dissipating baffle plates are positioned on opposite sides of the lamp. A cover is posi tioned over the lamp and baffle plates to direct the cooling air rising adjacent the lamp toward the rear of the projector. A film advance mechanism is housed in the case and includes an arm which engages the film sprocket holes only during the advancing operation.

PATENTEU JUL] 3l97l 3593 0153 SHEET 2 UF 4 INVENTOR [0a m: Mumvqz ATTORNEY i llllllI-lll' ul l ln 14 II. I!!! I I '17 I Ill/1 I!!! I III/ I!!! I 11/1! I I!!! I I all I III SHEET 3 BF 4 PATENTED Jun 3m m T N E V m VENTILATING MEANS FOR LIGHT SOURCE FOR PROJECTOR This application is a division of application, Ser. No. 715,621, filed Mar. 25, I968, for projector.

BACKGROUND AND SUMMARY OF THE INVENTION This invention relates to a simple, safe and silent projector for individual and small group instruction. In the illustrated embodiment, the projector is adapted for use with conventional filmstrips ol' the type commonly used by educational institutions as a supplement to regular teaching methods. The potential for this system has never been fully realized since conventional projectors are complex, expensive. and dangerous when operated by small children.

In a broad sense, this invention relates to a filmstrip projector having a molded plastic case enclosing the projection apparatus. A stand for adjustably supporting the case between a horizontal and an inclined position is attached to each side by means of an integral cylindrical ear adjacent the rear of the case and a clamping means at the front of the case. The stand comprises a pair of rods positioned on opposite sides of the case, each rod being rotatably mounted about the cylindrical ear. The stand also includes a segment forming an arc ofa circle about the cylindrical ear and which is releasably secured by the clamping means to the front of the case. By releasing the clamping means, the inclination of the projector relative to the stand may be easily varied by merely rotation the projector about the axes of the two cylindrical ears.

The case of the projector generally comprises a pair of substantially parallel sidewalls, upper and bottom walls having air vents therein, and front and rear walls. An electric lamp is mounted at a center location within the case, and a pair of parallel baffle plates are mounted on opposite sides of the lamp. An inverted U-shaped cover is positioned above the lamp and baffle plates, the cover having an inclined upper transverse surface for deflecting the air rising adjacent the lamp to the vent holes at the rear of the case upper wall.

The projector also includes a film advance mechanism which incorporates two closely spaced parallel plates defining a passageway for the filmstrip through the projector. One of the plates has an aperture opening to the area occupied by the sprocket holes of the film and which extends in the direction of film advance. A cam is positioned on one side of this plate adjacent the aperture and also extends in the direction of film advance. An advancing slider is mounted on the plate for translation between a rear and forward position, the slider having an elongated extension with a cam follower at the end thereof which is adapted to engage the cam when the slider is translated between the rear and the forward positions. A transverse arm is also positioned at the end of the extension such that when the cam follower engages the cam, the arm is projected through the aperture and into engagement with the sprocket holes of the film. Upon continued translation, the film is advanced a distance corresponding to the length of'the cam.

It is an object of the present invention to provide a projector which is so simple in design that it may be easily operated by a child, and thus may be used individually or in a small group without the necessity of a teacher being present. It is a further object to provide a projector which may be easily and quickly set up," and wherein the body of the projector is supported by a curved steel stand that doubles as an elevating device and carrying handle. The projector can be tilted up to 30 elevation simply by sliding it up the steel stand am; locking it with two knobs. Thus. the use of books and other makeshift props under the projector is eliminated. I

It is also an object of this invention to provide a projector which incorporates a frame advance mechanism which is completely free of the film when it is not being actuated. Thus, a child could pull as hard as possible on the film up or. down, and the film will slide freely, undamaged in either direction.

It is still another object to provide a projector wherein the outer walls stay cool during operation without the need for a cooling fan. A double wall construction is utilized to dissipate the heat of the lamp by the normal convection currents which pass the walls on each side of the lamp. The elimination of the cooling fan thus avoids the danger from rapidly turning blades. Also, the operation is absolutely silent which is a necessity when the projector is used in close proximity of a student.

These and other objects and advantages of the present invention will readily become apparent to one skilled in the art from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a perspective view showing the projector case and its associated stand;

FIG. 2 isa horizontal sectional view taken along the line 2-2 of FIG. 1;

FIG. 3 is a vertical sectional view FIG. 2;

FIG. 4 is a vertical sectional view taken along the line 4-4 of FIG. 2;

FIG. 5 is a fragmentary front view of the associated advancing slider;

FIG. 6 is a fragmentary rear view of the backplate and its associated advancing slider;

FIG. 7 is an enlarged sectional view taken along the lines -7 of FIG. 6',

FIG. 8 is a view similar to FIG. 7 showing the cam follower engaged during the film advance operation; and

FIG. 9 is a view taken along the line 9-9 of FIG. 8.

taken along the line 33 of backplate and its DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, a projector incorporating the features of the present invention is designated generally at 10. The outer case of the projector comprises an upper section I I and a lower section II which are joined by suitable bolts I2 to form an enclosure for the projection apparatus. The case may be described as a somewhat rectangular box having two parallel sidewalls I3, and upper wall 14, a bottom wall 15, a front end 16, and a rear end l7.

As will become apparent from the following description, the two case sections II and II are themselves identical in configuration, a fact which greatly contributes to cost reduction and simplicity of design. The case is preferably formed from a molded high-impact thermoplastic material, such as the acryIonitrile-butadiene-styrene thermoplastic resin Cycolac, produced by the Marbon Chemical Division of Borg-Warner Corporation. The case is suitably shaped to provide means for attaching the various internal projector components. The upper wall 14 is provided with a plurality of air vents I8 and I8 (note FIGS. 3 and 4) while the lower wall 15 has similar vents l9 and I9. v

Viewing FIG. 2, it will be seen that the internal projection apparatus includes as essential elements an electric lamp as sembly 20, a rear access door assembly 27, a lens condenser assembly 40, a film guide and advance mechanism 50, and a forward focusing lens 80.

The lamp assembly 20-includes a standard projector lamp 2l having a bayonet base for mounting in a conventional socket 22. The socket is connected to an appropriate electrical wire (not shown), and is suitably mounted in the case by means ofa strap 23.

A pair of baffle plates 25 are mounted on opposite sides of the lamp in generally parallel and spaced relation to the sidewalls I3. The plates 25, which may be formed from extruded aluminum, include a plurality of vertically extending transverse ribs 26 which are designed to facilitate heat dissipation and which may be positioned either on one or both sides of the plate.

Access to the lamp 2] for replacement is provided by the rear access door assembly 27. As seen in FIG. 3, the assembly 27 includes a back 28 which pivots about the hinge pin 29.

he back 28 is releasably secured at its upper end to the case y a nylon screw 30 which engages a sheet metal nut 31 lipped to the back. Thus, upon withdrawal of the screw 30. he back 28 swings to a generally horizontal position for easy ccess to the lamp.

The back 28 also retains a pair of rear baffie plates 25' vhich are designed for alignment with the baffie plates 25 vhen the back is closed. The baffle plates 25' may include ransverse ribs 26' for dissipating heat in a manner similar to he ribs 26. A back reflector 32. which preferably has a :hromed surface, is secured to the forward end of the plates 25' and is designed to reflect the light from the lamp 2I hrough the lens condenser assembly. The back 28 may also nclude an aperture 33 for an electric cord. as well as a switch l4.

The baffle plates 25' are secured to rear door 28 by rivets l8". Pivot pin 29 rotatably passes through apertures in ears 28' fixed to the flanges 25 on baffle plates 25'. The ends of )lVDl pin 29 are fixed to blocks 29" fixed to the sidewalls I3 of he case.

A cover 36, having a generally inverted Ushape in cross iection. is positioned above the lamp 2t and baffle plates 25 or the purpose of directing the flow of cooling air. The cover 56. which may be made from sheet metal. includes an upper :ransverse wall or surface 37 and two parallel depending side Flanges or edges 38 (FIG. 4) which are generally aligned in a :lirection parallel to the baffle plates 25. In the embodiment shown. the edges 38 extend downwardly to a point adjacent the bottom of the plates 25 to overlie and substantially enclose the entire lamp assembly. It should be understood, however. that the side edges 38 could be designed to extend only to the top portion of the baffle plates 25, or to any intermediate position therealong without impairment of the cooling effect. If the side edges 38 extend only to the top of the plates. the edges may also be designed to lie in the same plane as the plates rather than lying outside of this plane as shown in FIG. 4.

Positioned immediately above the lamp 2| is a light deflector 39 which is suitably mounted to the upper section II ofthe case. The deflector 39 serves to prevent the bright light ofthe lamp from being reflected through the openings I8 by the transverse surface 37.

Viewing FIG. 4. it will be apparent that there exist in the present design two independent air passages for dissipating the heat generated by the lamp. In the first and primary passage (designated by the solid arrows in FIGS. 3 and 4). the air which initially enters through the lower air vents I9 and 19' passes immediately adjacent to the lamp 21 within the area defined by the side edges 38 of the cover. the back reflector 32 and the condenser lens assembly 40. The air is warmed by contact with these surfaces (as well as the baffle plates 25) and continues to rise until it reaches the transverse surface 37 which is inclined toward the rear of the case to direct the flow through the upper vents 18' (note FIG. 3). By this arrangement. the warm air is directed away from the film as well as the areas which come in contact with the operator's hands. It will be noted that if the side edges 38 extend only to the top of the plates 25. the plates themselves will serve as the boundary for the primary passage.

In the secondary cooling system (designated by the broken arrows). a portion of the air entering through the lower vents l9 and [9 passes along the wall formed by the outside surface of the side edges 38 to the upper vents I8. This current of air serves to insulate the sidewalls [3 of the case from the warm elements of the projector such that the sidewalls 13 remain cool and may be touched without danger of burning.

The lens condenser assembiy 40 includes a heat filter 41, a meniscus condenser 42. and a biconvcx condenser 43 which are aligned in the direction of light projection. A suitable frame 44 is designed to retain the three elements of this assembly within the case.

The film St is designed to be inserted through a passageway in the film advance assembly 50 defined by a back plate 52 and a front plate 53, (note FIGS. 2-3). The two plates may be molded from a high-strength. heat-resistant plastic material such as the polyamide resin Zytel. which is sold by DuPont. They are mounted in the case by a conventional structure which has not been illustrated in detail herein. To facilitate retention of the film 51 adjacent the outer ends of the passageway, a semicircular recess 45 may be formed in the case. (note FIG. 3).

As seen in FIGS. 5-6. the film passageway across the backplate 52 includes a vertical channel defined by the edge abutments 54 and 54 which guide the film 51 past a rectangular opening 55. The opening 55 serves to frame the light emanating from the lamp 2! such that when the individual film image is aligned with the opening. the projected picture will be properly *framed on the screen. The channel may also incorporate a finger 46 on either side of the opening 55 (see also FIG. 2) projecting into said channel to reduce the amount of transverse clearance in the passageway at the point of projection and thereby prevent inadvertent changes of focusing, and also to prevent the film from moving longitu dinally while arms 72 are not in the sprocket holes.

The back plate 52 further includes a transversely directed side arm 56 positioned along each vertical edge. the arms having a cutout 57 in the upper portion thereof. A vertical slot 58 is positioned in the body of the plate 52 on each side of the opening 55, and an aperture 59 is positioned below the open ing 55 such that it opens to the area of the sprocket holes of the film 51. A cam 60 is positioned on the side of the plate 52 opposite the film 51 and in general alignment with the aperture 59 but in spaced relation thereto, see FIGS. 79. The cam 60 is bifurcated (FIG. 9) and includes a forward camming surface 61 and a rear camming surface 62.

When the backplate S2 is mounted in the case, it will be seen in FIGS. I and 3 that the side arms 56 are positioned in appropriate slots in the case sidewall 13 such that the arms are substantially flush with the outer surfaces of the walls. This structure gives rise to a pleasing appearance as well as increased rigidity.

An advancing slider member 65 is associated with the backplate 52 to complete the film advance mechanism. The member 65 includes oppositely extending finger-engaging sur faces 66 which are designed to pass through the cutouts 57, such that the member is retained to the plate 52. The member 65 is also retained by two longitudinal shoulders 67 which are designed to be received in the slots 58 of the plate. The midportion of the member comprises a crossbar 68 from which a longitudinal extension 69 projects toward the aperture 59 and cam 60. The lower end of the extension 69 is genera'lfy T- shaped in cross section, the two outer extremities of the upper portion (as seen in FIG. 9) being a cam follower 71 and the remaining portion being a transverse arm 72 which is directed toward the aperture 59.

During the film advance operation, the member 65 is translated between a rear (rest) and forward (actuated) position. (note FIG. 6). The member is controlled and guided during this translation by the interaction between the surfaces 66 and cutouts 67. as well as between the shoulders 67 and slots 58. It will be seen that the shoulders 67 limit the extent of the translation in both directions by engaging the ends of the slots 58.

As the member advances to the forward position, the cam follower 71 of the extension 69 engages the forward camming surface 61. This in turn causes the transverse arm 72 to pass through the opening 59 and engage the sprocket holes of the film 51. (note FIGS. 7-8). Upon continued translation, the follower 7I advances the film until the bottom end of the cam 60 is reached. at which point the arm 72 releases the film and withdraws through the aperture 59.

The member 65 and plate 52 may have an interconnecting spring 73 to automatically return the member to its rear posi tion. In the illustrated embodiment. the member includes a groove 74 along the back surface of the crossbar 68 to provide a clearance for the spring 73.

Upon translation of the member from its forward to its rear position, the follower 7| engages the rear camming surface 62 such that the arm 72 will be completely removed from the aperture 59 during the return niovement. The inherent resilience of the extension 69 provides sufficient flexibility to permit the required transverse movement of the arm 72.

It will be apparent that by properly determining the length of the cam 60 (designated D in FIG. 6), the film 51 can be made to sequentially advance a predetermined distance. By design, this distance will correspond to the distance between the individual frames on the film 51 such that upon actuation of the member 65, the film will advance to the next picture frame without further adjustment. It will also be seen that the crossbar 68 is designed to cover the aperture 55 during the advancing operation such that the new frame will not be projected on the screen until the member is released.

It will now be appreciated that the advance mechanism engages the film only during the advancing operation. At all other times the film is completely free of the mechanism and may be fed through the assembly and framed merely by inserting and adjusting the film from above. Also, this feature protects the film from damage should it be given a sudden pull in either direction, as might be done by a child.

A conventional focusing lens 80 is supported by a housing 8] which is suitably secured in the case. The interconnection between the lens and housing, as shown for example in FIG. 3, provides a simple, push-pull focusing system.

The proje" is; is supported by a curved stand 86 which doubles as an elevating device and carrying handle. The stand may be made from a single piece of chrome-plated steel rod which is suitably formed or bent into the desired final shape. The stand 86 is joined to the case of the projector by a connecting structure which includes a cylindrical ear 82 positioned on each sidewall 13 adjacent the rear of the projector, and a clamp 83 positioned on each sidewall adjacent the front of the projector. The clamp 83 includes a lip 84 for engaging the stand, and is releasably connected to the case by means of a threaded knob 85 which engages a nut 79 permanently secured in the case.

A portion of the stand 86 is positioned on each side of the projector, the two portions being identical in shape and joined by a connecting segment across the top of the projector. The free end of the stand on each side of the case is formed into the shape of a cylindrical loop 87 which is adapted to be rotatably mounted on and retained by the car 82.

Adjacent the loop 87 is a vertical segment 88 extending downwardly a sulficient distance to lift the case from the supporting structure or table. Next is a horizontal segment 89 which extends for a distance comparable to the overall length of the projector and which is designed to rest upon the supporting table. The opposite end of the horizontal segment 89 is joined to an arcuate segment 90 which is formed into a section of a circle having a center which corresponds to the center of the cylindrical loop 87, The arcuate segment 90 extends above the projector and is joined to the arcuate segment of the opposite side of the case by a connecting segment 9! which also serves as a carrying handle for the projector.

As will be seen in FIG. 2, the lip 84 of the clamp presses the arcuate segment 90 of the stand against the body of the case to lock the stand in position when the knob 85 is tightened. When the knob 85 is loosened, the clamp releases the stand for rotation about the axes of the cylindrical cars 82. By this arrangement, the inclination projector may easily be adjusted anywhere between the horizontal and an angle of approximately 30. If desired, a rubber feet 92 may be positioned on the horizontal segment 89 of the stand to increase the frictional contact between the stand and its supporting table.

While a specific embodiment of this invention has been disclosed in considerable detail herein, it should be understood that the scope of the invention is to be determined by that of the following claims only.

1 claim;

1. In a film projector having an electric lamp for projecting the film image on a remote screen, and further including an outer case having ajpair of sidewalls, upper and bottom walls each having a plurality of air vents therein disposed forwardly of the rear end of the ease and said case having air vents at its upper rear end; a cooling system for dissipating the heat generated by said electric lamp comprising, a pair of substantially parallel baffle plates mounted on opposite sides of said lamp and in general parallel relation to said case sidewalls, said baffle plates extending upwardly from a point adjacent the bottom of said lamp at least to a point adjacent the top of said lamp, an inverted U-shaped cover positioned above said lamp and said baffle plates, and including an upper transverse wall and two parallel depending side flanges, said upper transverse wall being inclined upwardly toward the upper rear end of said case to a point above said vents at said upper rear end of the case, said side flanges extending downwardly from said transverse well at least to a point adjacent the top of said baffle plates to generally form a continuation of the walls formed by said baffle plates in the upward direction, whereby a first cooling air passage is defined by the area enclosed by the two side flanges of said cover such that the portion of the rising air currents encompassed by said area are deflected by said transverse wall toward the vents at the upper rear end of said case, and a secondary cooling air passage is defined by the area outside the two side flanges such that the air currents enclosed by said latter area exit directly through the vents in said upper wall, said cover preventing air from said first cooling passage from passing to the vent openings in the upper wall, through which air from the secondary cooling passage pass.

2. In a film projector having an electric lamp for projecting the film image on a remote screen, said projector including an outer case comprising a pair of sidewalls, upper and bottom walls having air vents therethrough, and front and rear walls, a cooling system for dissipating the heat generated by said electric lamp without the need for a cooling fan comprising, a first air passage about said lamp defined by a pair of substantially parallel baffle plates mounted on opposite sides of said lamp and in generally parallel relation to said case sidewalls, said baffle plates extending upwardly from a point adjacent the bottom of said lamp at least to a point adjacent the top of said lamp, and an inverted U-shaped cover positioned above said lamp and including an upper transverse wall and two parallel depending side flanges, said side flanges overlying said baffle plates and extending downwardly from said transverse wall to a point beyond the top of said baffle plates, whereby a portion of the rising air currents caused by the heat of said lamp while in operation is directed from said bottom wall vents along the surfaces of said baffle plates and the inside surfaces of said side flanges to said transverse wall, said transverse wall having means to direct said currents where they are directed in a transverse direction rearwardly to exit through a designated portion of the vents in said upper case wall located at the rear end, and a secondary air passage defined by the outer surfaces of said cover side flanges and the two sidewalls of said case, whereby the remaining portion of the rising air currents is directed from said bottom wall vents through said secondary air passage and along said case sidewall to the vents in said upper case wall which are located forwardly of the vents which are located at the rear end of the upper case wall.

3. A cooling system for a film projector as defined in claim 2, wherein said baffle plates include heat dissipating transverse ribs.

4. A film projector comprising a case having first, second andthird vent openings, a lamp assembly in the case, and airdeflecting means to provide a first passageway for heated air from above the lamp to pass out ofthe casing through said first vent openings of the case and a pair of passageways at op posite sides of said assembly to allow for flow of air into the case through said second vent openings of the case, through said pair of passageways and out of the casing through said third vent openings of the case, and to block heated air from above the lamp. from passing to said third vent openings and to event air from said pair of passageways from passing to said st vent openings.

5. The combination of claim 4, said case having sidewalls, I upper wall, a bottom wall and an upper rear wall, said third nt openings being formed in said upper wall, said second nt openings being formed in said bottom wall and said first nt openings being formed in said rear upper wall, said first lssageway extending from the top of the lamp to the first nts in said upper rear wall, said pair of passageways extendg from the second vents in said bottom wall to the third vents said upper wall.

6. The combination of claim 5, said lamp assembly compris g a lamp support, a lamp mounted on said support, said sup- )rt comprising a pair of baffle sideplates disposed at opposite ies of the lamp and extending upwardly from adjacent the ittom of the lamp to adjacent the top of the lamp and said r-deflecting means comprising a top transverse wall extendg from the forward upper side of the lamp to a point between e third vents in the upper wall of the case and the first vents the upper rear wall of the case.

7. The combination of claim 6, and said deflecting means rther comprising side flanges extending downwardly from id top transverse wall, said side flanges being spaced inardly from the sidewalls of the case and forming said pair of issageways with said sidewalls of the case and connecting the cond vents in the bottom wall of the case with the third vents the upper wall of the case.

8. The combination of claim 5, said case having a rear openg disposed below the upper rear wall of the case, said lamp lpport having a back wall substantially closing said rear aening of said case.

9. The combination of claim 8, said lamp support being lvoted at its lower end, to said case and being tiltable igether with its back wall rearwardly to expose its upper end, 1d releasable means to latch the upper end of said lamp supart to the case to hold said support against movement, with lid back wall of said lamp support closing said rear opening of said case.

10. The combination of claim 9, said lamp support being open at the top, said lamp support having a socket at its lower end to receive the base of the lamp, and said lamp being removable and replaceable, upon releasing the latch means and tilting the lamp support and its back wall rearwardly about its pivot, through the upper open end of said lamp support.

II. The combination of claim 6, and a light deflector fixed to said lamp support and disposed rearwardly of said lamp to deflect light forwardlyv 12. The combination of claim 6, said baffle plates having cooling ribs thereon.

l3. The combination of claim 6, and a light deflector mounted on said lamp support and disposed between said lamp and said transverse wall of said air-deflecting means and preventing light rays from the lamp from passing to said first vents.

14. The combination of claim 4, means to pivot the lower end of said lamp assembly to said case, and releasably latch means to hold said lamp assembly within said case, said lamp assembly being tiltable backwardly upon releasing said latch means.

[5. The combination of claim 14, and said lamp assembly comprising a lamp socket to receive the base of the lamp, and said assembly being open at the top to permit replacement of the lamp when said lamp assembly is tilted backwardly.

16. The combination of claim 15, said case having an opening at its rear end through which the lamp assembly may tilt backwardly, and said assembly including a back wall to close said rear opening in said case.

17. The combination of claim 5, and said air-deflecting means comprising means to deflect air rising from the space around said lamp, rearwardly toward said first vent openings.

18. The combination of claim 17, and means to block rays from the lamp from passing to said first vent openings.

19. The combination of claim 18, and means to pivot the lower rear end of said assembly to the case. 

1. In a film projector having an electric lamp for projecting the film image on a remote screen, and further including an outer case having a pair of sidewalls, upper and bottom walls each having a plurality of air vents therein disposed forwardly of the rear end of the case and said case having air vents at its upper rear end; a cooling system for dissipating the heat generated by said electric lamp comprising, a pair of substantially parallel baffle plates mounted on opposite sides of said lamp and in general parallel relation to said case sidewalls, said baffle plates extending upwardly from a point adjacent the bottom of said lamp at least to a point adjacent the top of said lamp, an inverted U-shaped cover positioned above said lamp and said baffle plates, and including an upper transverse wall and two parallel depending side flanges, said upper transverse wall being inclined upwardly toward the upper rear end of said case to a point above said vents at said upper rear end of the case, said side flanges extending downwardly from said transverse well at least to a point adjacent the top of said baffle plates to generally form a continuation of the walls formed by said baffle plates in the upward direction, whereby a first cooling air passage is defined by the area enclosed by the two side flanges of said cover such that the portion of the rising air currents encompassed by said area are deflected by said transverse wall toward the vents at the upper rear end of said case, and a secondary cooling air passage is defined by the area outside the two side flanges such that the air currents enclosed by said latter area exit directly through the vents in said upper wall, said cover preventing air from said first cooling passage from passing to the vent openings in the upper wall, through which air from the secondary cooling passage pass.
 2. In a film projector having an electric lamp for projecting the film image on a remote screen, said projector including an outer case comprising a pair of sidewalls, upper and bottom walls having air vents therethrough, and front and rear walls, a cooling system for dissipating the heat generated by said electric lamp without the need for a cooling fan comprising, a first air passage about said lamp defined by a pair of substantially parallel baffle plates mounted on opposite sides of said lamp and in generally parallel relation to said case sidewalls, said baffle plates extending upwardly from a point adjacent the bottom of said lamp at least to a point adjacent the top of said lamp, and an inverted U-shaped cover positioned above said lamp and including an upper transverse wall and two parallel depending side flanges, said side flanges overlying said baffle plates and extending downwardly from said transverse wall to a point beyond the top of said baffle plates, whereby a portion of the rising air currents caused by the heat of said lamp while in operation is directed from said bottom wall vents along the surfaces of said baffle plates and the inside surfaces of said side flanges to said transverse wall, said transverse wall having means to direct said currents where they are directed in a transverse direction rearwardly to exit through a designated portion of the vents in said upper case wall located at the rear end, and a secondary air passage defined by the outer surfaces of said cover side flanges and the two sidewalls of said case, whereby the remaining portion of the rising air currents is directed from said bottom wall vents through said secondary air passage and along said case sidewall to the vents in said upper case wall which are located forwardly of the vents which are located at the rear end of the upper case wall.
 3. A cooling system for a film projector as defined in claim 2, wherein said baffle plates include heat dissipating transverse ribs.
 4. A film projector comprising a case having first, second and third vent openings, a lamp assembly in the case, and air-deflecting means to provide a first passageway for heated air from above the lamp to pass out of the casing through said first vent openings of the case and a pair of passageways at opposite sides of said assembly to allow for flow of air into the case through said second vent openings of the case, through said pair of passageways and out of the casing through said third vent openings of the case, and to block heated air from above the lamp from passing to said third vent openings and to prevent air from said pair of passageways from passing to said first vent openings.
 5. The combination of claim 4, said case having sidewalls, an upper wall, a bottom wall and an upper rear wall, said third vent openings being formed in said upper wall, said second vent openings being formed in said bottom wall and said first vent openings being formed in said rear upper wall, said first passageway extending from the top of the lamp to the first vents in said upper rear wall, said pair of passageways extending from the second vents in said bottom wall to the third vents in said upper wall.
 6. The combination of claim 5, said lamp assembly comprising a lamp support, a lamp mounted on said support, said support comprising a pair of baffle sideplates disposed at opposite sides of the lamp and extending upwardly from adjacent the bottom of the lamp to adjacent the top of the lamp and said air-deflecting means comprising a top transverse wall extending from the forward upper side of the lamp to a point between the third vents in the upper wall of the case and the first vents in the upper rear wall of the case.
 7. The combination of claim 6, and said deflecting means further comprising side flanges extending downwardly from said top transverse wall, said side flanges being spaced inwardly from the sidewalls of the case and forming said pair of passageways with said sidewalls of the case and connecting the second vents in the bottom wall of the case with the third vents in the upper wall of the case.
 8. The combination of claim 5, said case having a rear opening disposed below the upper rear wall of the case, said lamp support having a bAck wall substantially closing said rear opening of said case.
 9. The combination of claim 8, said lamp support being pivoted at its lower end, to said case and being tiltable together with its back wall rearwardly to expose its upper end, and releasable means to latch the upper end of said lamp support to the case to hold said support against movement, with said back wall of said lamp support closing said rear opening of said case.
 10. The combination of claim 9, said lamp support being open at the top, said lamp support having a socket at its lower end to receive the base of the lamp, and said lamp being removable and replaceable, upon releasing the latch means and tilting the lamp support and its back wall rearwardly about its pivot, through the upper open end of said lamp support.
 11. The combination of claim 6, and a light deflector fixed to said lamp support and disposed rearwardly of said lamp to deflect light forwardly.
 12. The combination of claim 6, said baffle plates having cooling ribs thereon.
 13. The combination of claim 6, and a light deflector mounted on said lamp support and disposed between said lamp and said transverse wall of said air-deflecting means and preventing light rays from the lamp from passing to said first vents.
 14. The combination of claim 4, means to pivot the lower end of said lamp assembly to said case, and releasably latch means to hold said lamp assembly within said case, said lamp assembly being tiltable backwardly upon releasing said latch means.
 15. The combination of claim 14, and said lamp assembly comprising a lamp socket to receive the base of the lamp, and said assembly being open at the top to permit replacement of the lamp when said lamp assembly is tilted backwardly.
 16. The combination of claim 15, said case having an opening at its rear end through which the lamp assembly may tilt backwardly, and said assembly including a back wall to close said rear opening in said case.
 17. The combination of claim 5, and said air-deflecting means comprising means to deflect air rising from the space around said lamp, rearwardly toward said first vent openings.
 18. The combination of claim 17, and means to block rays from the lamp from passing to said first vent openings.
 19. The combination of claim 18, and means to pivot the lower rear end of said assembly to the case. 